1. Field of the Invention
The present invention relates to a device for correcting the meandering motion of a belt so as to prevent a deviation of the belt wound around a rotary body such as a roller.
2. Statement of the Related Art
Conventionally, there are known conveyor belts for conveying materials to be conveyed and driving force transmitting belts that are wound around a rotary body such as a roller and adapted to transmit the rotational force of the roller.
For instance, such a belt is used in a heat development and transfer apparatus in which a light-sensitive material exposed imagewise to light is superposed on an image-receiving material, and the superposed materials are wound around an outer periphery of a heating drum. In this state, the light-sensitive material is heat developed by heating and, at the same time, the image is transferred onto the image-receiving material so as to obtain an image. In this heat development and transfer apparatus, the belt is used as a clamping and conveying means at the time when the superposed light-sensitive material and image-receiving material are wound around the outer periphery of the heating drum.
In this case, an endless belt is used as the belt and is wound around a plurality of rollers, and an outer side thereof is brought into pressure contact with the outer periphery of the heating drum. The arrangement is such that after the imagewise exposed light-sensitive material is superposed on the image-receiving material, the superposed materials are fed between the heating drum and the endless pressure-contact belt and are wound around the outer periphery of the heating drum.
The respective materials are clamped and conveyed for a predetermined time in a state in which they are superposed on each other between the endless pressure-contact belt and the heating drum heated to approximately 90.degree. C. As a result, the light-sensitive material is heat developed, and the image formed on the light-sensitive material is transferred onto the light-receiving material.
However, with this endless pressure-contact belt, which is wound around a plurality of rollers and is brought into pressure contact with the outer periphery of the heating drum, when the belt rotatively moves together with the heating drum, a deviation of the belt from a predetermined course occurs relative to the rollers around which the belt is wound.
Consequently, at the time when the light-sensitive material and the image-receiving material are superposed and conveyed in a clamped state, an incorrect superposition can occur, which results in nonuniformity in development and transfer of the image, thereby making it difficult to obtain a desirable image.
In this case, in order to eliminate a deviation of the endless pressure-contact belt wound around the rollers, it is necessary to form the configuration and dimensions of the endless pressure-contact belt with high accuracy and accurately adjust the alignment between the rotational axes of the rollers and the heating drum, the belt winding positions, the tension of the belt, and the like. With such a method, however, since high accuracy is required, there are problems in that cost inevitably becomes high and that a lack of stability is experienced when the apparatus is used for extended periods of time.
It is conceivable to provide an arrangement in which a flange is merely formed at each opposite end of the roller around which the endless pressure-contact belt is wound, so as to forcedly prevent a deviation in the belt winding position. With this arrangement, however, there are drawbacks in that the widthwise side portion of the belt can be damaged by interference with the flange, and that the belt driving force increases or decreases intermittently, thereby rendering the conveying speed nonuniform.